Well, here's a hint. In February, before Concepcion, the Cal Supremes decided Sonic Calbassas A., Inc. v. Moreno (2011) 51 Cal.4th 659. This was a wage and hour case, in which Cal Supremes held that an arbitration agreement did not bar an employee from using a statutory, pro-employee administrative procedure before the State Labor Commissioner to try to get a favorable ruling instead of going straight to contractual arbitration.

The employer filed a cert petition, to which the US Supreme Court tersely responded:

The petition for a writ of certiorari is granted. The judgment is vacated, and the case is remanded to the Supreme Court of California for further consideration in light of AT&T Mobility LLC v. Concepcion, 563 U.S. ___ (2011).